Facebook, Twitter, Google+, and other social networking websites present items of content including text, images, and videos to their users using a content stream that is in reverse-chronological order (e.g., with the topmost item in the stream being the last in time) or ordered according to an interestingness algorithm (e.g. with the topmost item in the stream having the highest interestingness score according to the algorithm) and/or a personalization algorithm.
Such content streams are now also being used by websites such as Yahoo! and Google that include multiple services such as a news service and a web-search service. Personalization of these content streams tends to be based on content-based filtering (e.g., using implicit relevance feedback such as click-throughs, click-ons, mouse-overs, or mouse-hovers on news articles), collaborative filtering using profiles of similar users, and/or a hybrid of the two.